Caravan Rollovers etc

[Gafferbill]

Hi

Reading the forums I am continually amazed at drivers confidence in their outfits when at speed.

Most say they tow at 60, some at 70 and a few at 80mph.

Yet even a new van will have serious safety isues.

The tyres could be weakened by being flat spotted, due to not moving for months. The pressures could be too low.

The nose weight could be wrong. The load could be placed too high. On older vans the brakes could be worn, tyres perished.

Do all of these confident drivers jack their vans to take weight off the tyres and suspension when not in use.

Check the tyre pressures before setting off and the state of the tyres. Load their vans properly.

Maybe they do.

I have had the misfortune to witness 3 caravan rollovers from the cab of my truck as they happened. They all had one thing in common..... the driver was trying to go too fast.

The caravan started to snake caused by an incident, the caravan took control of the rear end of the car, the caravan flipped over and took the car with it.

Fortunately none of the occupants were seriously hurt.

One had a tyre blow out. One was trying to overtake an HGV and got buffeted by the pressure wave. The other I do not know what started the snake, could have been a gust of wind.

In all three the caravan disintergrated like match wood spreading debris everywhere.

The only impressive thing is that the hitch remained attached in all three.

I have lost count of the number of rollovers I have come across after they have happened.

I deduce from this that car and caravan combinations are all

unstable and subject to a multitude of safety isues.

I drive mine and look after it accordingly.

No doubt I am about to be told I have got it all wrong!

 

[Lutz]

Without going into a discussion whether they were going too fast or any technical reasons why the outfits were unstable in the first place or whether the reason for the accident was a combination of both, one thing is for sure, in all cases the drivers reacted wrongly. A caravan doesn't flip over suddenly. It will show signs of impending instability which will get pregressively worse unless one reacts accordingly. Obviously, the drivers were not alert to the signs or ignored them.

 

[Gumbo]

Gaffer wrote

" The tyres could be weakened by being flat spotted, due to not moving for months. The pressures could be too low.

The nose weight could be wrong. The load could be placed too high. On older vans the brakes could be worn, tyres perished.

Do all of these confident drivers jack their vans to take weight off the tyres and suspension when not in use.

Check the tyre pressures before setting off and the state of the tyres. Load their vans properly"

I would hope so !!!! I do believe Twin Axles make it a shade safer if you have a blow out ?????

 

[ghostrider]

Gaffer wrote

" The tyres could be weakened by being flat spotted, due to not moving for months. The pressures could be too low.

The nose weight could be wrong. The load could be placed too high. On older vans the brakes could be worn, tyres perished.

Do all of these confident drivers jack their vans to take weight off the tyres and suspension when not in use.

Check the tyre pressures before setting off and the state of the tyres. Load their vans properly"

I would hope so !!!! I do believe Twin Axles make it a shade safer if you have a blow out ?????

definatly twin axles so much more stable, came out of oulton park the other week( checked tyre pressure two days previous)

thought that looks a little low, got home checked it, only 4 psi in it, but didnt feel different whilst towing ,dead stable couldnt believe it

 

[Lutz]

I don't quite see what taking the weight off the tyres and suspension when not in use has to do with safety. If that were the case, what about all the cars standing around in showrooms or in car compounds sometimes for months on end? It may result in a temporary flatspot, but that will soon disappear after driving a few miles. The flatspot will generate rumbling for a short while until the tyre is round again, but that only has something to do with comfort, not safety.

As for twin axles being so much more stable, that implies single axles are inherently unstable, which is not necessarily the case. I had a blowout with my single axle a couple of weeks ago on the motorway and, although the outfit was almost at 100% weight ratio and the incident happened in a bend, the caravan stayed rock steady behind the car until I was able to come to a standstill. I only noticed because there was a big bang, followed by smoke billowing out of the wheelarch. By the time I stopped, the wheel rim was also damaged beyong repair.

 

[Gafferbill]

Without going into a discussion whether they were going too fast or any technical reasons why the outfits were unstable in the first place or whether the reason for the accident was a combination of both, one thing is for sure, in all cases the drivers reacted wrongly. A caravan doesn't flip over suddenly. It will show signs of impending instability which will get pregressively worse unless one reacts accordingly. Obviously, the drivers were not alert to the signs or ignored them.

I think panic takes over when it happens.

In theory we may know what to do but.....

 

[Lutz]

Without going into a discussion whether they were going too fast or any technical reasons why the outfits were unstable in the first place or whether the reason for the accident was a combination of both, one thing is for sure, in all cases the drivers reacted wrongly. A caravan doesn't flip over suddenly. It will show signs of impending instability which will get pregressively worse unless one reacts accordingly. Obviously, the drivers were not alert to the signs or ignored them.

Possible emergency situations, such as threatening snaking, can be mastered by practice and, once you have practiced a few times and you know what to do, the chances of panicking are dramatically reduced.

 

[Gafferbill]

I don't quite see what taking the weight off the tyres and suspension when not in use has to do with safety. If that were the case, what about all the cars standing around in showrooms or in car compounds sometimes for months on end? It may result in a temporary flatspot, but that will soon disappear after driving a few miles. The flatspot will generate rumbling for a short while until the tyre is round again, but that only has something to do with comfort, not safety.

As for twin axles being so much more stable, that implies single axles are inherently unstable, which is not necessarily the case. I had a blowout with my single axle a couple of weeks ago on the motorway and, although the outfit was almost at 100% weight ratio and the incident happened in a bend, the caravan stayed rock steady behind the car until I was able to come to a standstill. I only noticed because there was a big bang, followed by smoke billowing out of the wheelarch. By the time I stopped, the wheel rim was also damaged beyong repair.

Good description of what happens to a tyre in it's initial usage after it has been left standing for a while.

Whilst it is geting back into shape it is weakening the strength of the sidewalls permanently.

 

[Gafferbill]

Twin axles are definitely more stable with more safety margin as Gumbo and Ghostrider say

 

[Lutz]

I don't quite see what taking the weight off the tyres and suspension when not in use has to do with safety. If that were the case, what about all the cars standing around in showrooms or in car compounds sometimes for months on end? It may result in a temporary flatspot, but that will soon disappear after driving a few miles. The flatspot will generate rumbling for a short while until the tyre is round again, but that only has something to do with comfort, not safety.

As for twin axles being so much more stable, that implies single axles are inherently unstable, which is not necessarily the case. I had a blowout with my single axle a couple of weeks ago on the motorway and, although the outfit was almost at 100% weight ratio and the incident happened in a bend, the caravan stayed rock steady behind the car until I was able to come to a standstill. I only noticed because there was a big bang, followed by smoke billowing out of the wheelarch. By the time I stopped, the wheel rim was also damaged beyong repair.

Why should it weaken the sidewalls permanently? I have never heard of tyres being replaced on cars that have been standing around in compounds for a few months because there was a danger of them not being up to usage later.

 

[Lutz]

If twin axles were so much more safe why is there then a trend in the caravan industry for ever heavier single axles? 1800kg single axles are not uncommon any more. Years ago, practically everything over 1400kg was twin.

 

[Gafferbill]

Why should it weaken the sidewalls permanently? I have never heard of tyres being replaced on cars that have been standing around in compounds for a few months because there was a danger of them not being up to usage later.

Extra heat generation and extra flexing due to the flat spot damages the plys.

A similar effect happens with under inflation, only in this case to a far greater extent.

Not such a problem in car compounds as weight spread over 4 tyres so less deflection on each tyre and smaller flat spot.

Once sold not likely to happen again.

On caravans if used for 8 weeks of the year the other 44 are creating flatspots if the weight is not removed.

some are only used fo 2 weeks a year.

Damage done in first few miles of each trip.

The effect is cumulative.

Single axle caravans are cheaper to make, they just fit bigger rims and higher spec tyres.

 

[Lutz]

I still don't get it, Gafferbill. You say, "Extra heat generation and extra flexing due to the flat spot damages the plys.". What is flexing? The tyre is just not perfectly round for a while until the flatspot recovers, but it's not flexing any more because of the flatspot.

 

[Lutz]

ps: Are you suggesting that the caravan manufacturers are cutting corners regarding cost at the expense of safety? I think the main reason for the trend to single axles is to save weight, thereby increasing payload.

 

[Gafferbill]

Tyre care is important on caravans because of what we the owner ask of them. We are all different.

The guy who uses his caravan to go to weekly events for his work will not need to worry about flat spots or removing weight

You rarely need to worry about wear on a caravan tyre, it will perish first.

If you change your caravan every couple of years you would not worry either.

If you keep your caravan for several years with most of it's time in storage you need to take care.

All tyres deflect at their point of contact with the road as they rotate. Their main work is to support the weight. When they have had enough of doing this the side wall gives way.

Every rotation minutely brings this finite point nearer.

You can severly flatspot the tyre in prolonged storage.

Only one section of the tyre has been working supporting the weight. This section has to work hard to regain it's true shape and in doing so speeds up the degredation of the sidewall's finite life due to it's extra flexing.

As a tyre ages the rubber becomes more brittle and this effect is more exagerated.

Car and truck tyres do not last that long so this problem rarely shows itself on these vehicles.

My caravan has an Alco chassis with rubber suspension. They recomend that you store the caravan on its Alco axle stands( an Alco aftermarket product) to take the weight off the tyres and suspension. This is so the rubber can asume its no weight position to minimise damage and prolong life.

Caravan manufactures are not compromising on safety by fitting single axles. They are safe when new, it's what the owners do in the way of maintainance and use once bought.

Manufactures tend to fit lower specification tyres at lower pressures on twin axles anyway.

Fit higher specification tyres on a twin axle yourself and you have increased the safety margins.

One thing you do get with twin axles that you do not get with singles is tyre squirm ( when turning) and this is very detrimental to the sidewalls and tread wear.

Made worse by the fact that pressures are lower.

 

[Lutz]

I think I understand now, but I would have thought that the degree of extra flexing due to a flatspot would only be significant if the tyre lost a significant amount of air pressure during storage, i.e. the flatspot was relatively large. I have always been told to raise tyre pressure to well above normal running pressure while the caravan is in storage to prevent that from happening.

 

[Gafferbill]

I think I understand now, but I would have thought that the degree of extra flexing due to a flatspot would only be significant if the tyre lost a significant amount of air pressure during storage, i.e. the flatspot was relatively large. I have always been told to raise tyre pressure to well above normal running pressure while the caravan is in storage to prevent that from happening.

Raising tyre pressures in storage is better than doing nothing but not as good as removing the weight altogether.

Winter wheels are another solution and give added security to the caravan.... the theif has to fit some wheels before they can tow it away!

 

[Lutz]

I think I understand now, but I would have thought that the degree of extra flexing due to a flatspot would only be significant if the tyre lost a significant amount of air pressure during storage, i.e. the flatspot was relatively large. I have always been told to raise tyre pressure to well above normal running pressure while the caravan is in storage to prevent that from happening.

There must be around 100 caravans on the site where I store my caravan. I had a wander around and nobody takes the load off the tyres.

 

[Gafferbill]

There must be around 100 caravans on the site where I store my caravan. I had a wander around and nobody takes the load off the tyres.

That is the reason I made the origional post.......

 

[Gafferbill]

Visit this website for excellent caravan tyre advice.....

http://www.caravan-advice.co.uk/caravan_tyres.html

 

[Lutz]

The advice in the website to store tyres upright applies only if the tyres are mounted on wheels, not if tyres are stored on their own. By law, we have to have winter tyres here and, in order not to have to keep buying new wheels every time I change car (which is every year), I have the tyres removed from their rims at the start and end of each winter season. The tyre dealers have always told me to store unmounted tyres lying horizontally.

 

[Gafferbill]

Visit this website for excellent caravan tyre advice.....

]http://www.caravan-advice.co.uk/caravan_tyres.html

http://www.caravan-advice.co.uk/caravan_tyres.html[/quote
Remember if you do, or are thinking of using winter wheels, check that your insurance allows them.

Some insist that a wheel clamp is fitted to your caravan at all times, when it is not in use.

I do not want to give bad information to anyone reading my posts